ATM-Mediated translocation of RanBPM regulates DNA damage response by stabilizing p21 in non-small cell lung cancer cells.

PURPOSE: Platinum-based chemotherapy remains a standard-of-care for most patients with advanced non-small cell lung cancer (NSCLC). DNA damage response (DDR) induced by platinum or Etoposide activated a panel of cell cycle-regulatory proteins including p21 through p53 pathway. Previous studies have reported that RanBPM has been involved in various cellular processes such as DDR by interacting with multiple proteins. However, the underlying mechanism remains unclear. METHODS: NSCLC tissue microarrays were used for assessing the expression of RanBPM by immunohistochemical staining. The roles of RanBPM in the DDR of NSCLC progression was examined in in vitro cell lines and in vivo animal models. The regulation of RanBPM on protein stability and ubiquitination levels were investigated by immunoblots and in vivo ubiquitylation assay. RESULTS: The level of p21 or RanBPM is lower in NSCLC than non-malignant tissues and has a highly positive correlation. Mechanistically, RanBPM protein physically interacts with p21, and RanBPM deubiquitinates p21 by recruiting a deubiquitinase USP11 to maintain protein stability of p21. RanBPM silencing significantly decreased p21 protein level. Conversely, RanBPM overexpression led to the accumulation of endogenous p21 protein regardless of p53 status. Functionally, RanBPM regulates DDR in a p21-dependent manner. Furthermore, DNA damage significantly promoted the nuclear translocation of RanBPM protein through ATM signaling pathways. CONCLUSION: RanBPM is a novel regulator of P21 protein stability, and plays a critical role in the regulation of DDR.

PLK1 maintains DNA methylation and cell viability by regulating phosphorylation-dependent UHRF1 protein stability.

PLK1 is a key serine/threonine kinase as well as a master mitotic regulator, but it has never been reported that PLK1 regulates DNA methylation. In the present study, we for the first time found that PLK1 inhibition disrupted global DNA methylation and elevated the expression level of tumor suppressor genes. Mechanistically, we found that PLK1 interacts UHRF1 protein to induce its phosphorylation at serine 265. Phosphorylation is required for the maintenance of UHRF1 protein stability by recruiting a deubiquitinase USP7. Conversely, PLK1 inhibition decreases UHRF1 protein interaction with USP7 and activates the ubiquitin-proteasome pathway, thereby accelerating UHRF1 protein degradation. UHRF1 degradation decreases the recruitment of DNMT1 to chromatin, and decreases the level of genome-wide DNA methylation, thereby elevating the expression of tumor suppressor genes and decreasing cell viability. We here presented the first report on the novel role of PLK1 in DNA methylation maintenance through UHRF1-DNMT1 pathway, and revealed a novel anticancer mechanism of PLK1 inhibitors.

AR antagonists develop drug resistance through TOMM20 autophagic degradation-promoted transformation to neuroendocrine prostate cancer.

BACKGROUND: Prostate cancer(PCa) is the most commonly occurring male cancer in the USA. Abiraterone or Enzalutamide have been approved for the treatment of metastatic castration-resistant prostate cancer (CRPC). However, the treatment-emergent neuroendocrine PCa (t-NEPC) may develop, resulting in drug resistance in about 10-17% CRPC patients. The detailed mechanisms remain unclear.. METHODS: The expression correlation of TOMM20 and AR in PCa was determined by analyzing publicly available datasets, or by IHC staining in tumor specimens. The protein interaction of TOMM20 and AR was validated by co-immunoprecipitation or GST pull-down assay. The impact of TOMM20 depletion on drug sensitivity were elucidated by assays of cell proliferation, invasion, sphere formation, xenograft growth and intravenous metastasis. The intracellular ROS level was measured by flow cytometry, and the NEPC transdifferentiation and characteristics of cancer stem-like cells were validated by RNA-seq, RT-PCR and western blotting. RESULTS: The protein level of TOMM20 is positively correlated with AR in PCa cells and specimens. TOMM20 protein physically interacts with AR. AR antagonists induced the protein degradation of TOMM20 through autophagy-lysosomal pathway, thereby elevating the intracellular ROS level and activating PI3K/AKT signaling pathway. When TOMM20 was depleted, PCa cells underwent EMT, acquired the characteristics of cancer stem-like cells, and developed resistance to AR antagonists. The stable depletion of TOMM20 promoted the transdifferentiation of PCa adenocarcinoma into NEPC and metastasis. Conversely, the rescue of TOMM20 re-sensitized the resistant PCa cells to AR antagonists. CONCLUSIONS: TOMM20 protein degradation induced by AR antagonists promoted the transdifferentiation of PCa to NEPC, thereby revealing a novel molecular mechanism by which AR antagonists develop drug resistance through mitochondrial outer membrane-mediated signaling pathway. These findings suggested that the decreasing or loss of TOMM20 expression in PCa tissues might become a useful predictor of PCa resistance to AR antagonists.

Network-Based Method to Investigate the Promoted Cell Apoptosis Mechanisms of Oridonin in OSCC through the RNA-Transcriptome.

The morbidity of oral cancer is high in the world. Oridonin is a traditional Chinese medicine that can effectively inhibit oral squamous cell carcinoma (OSCC) growth, but its mechanism remains unclear. Our previous data showed that oridonin inhibited CAL-27 cell proliferation and promoted apoptosis. Herein, we explored the mechanism and target of oridonin in human OSCC through RNA sequencing and integration of multiple bioinformatics analysis strategies. Differences in gene expression can be analyzed with RNA sequencing. Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene Ontology (GO), gene set enrichment analysis (GSEA), Disease Ontology (DO), and other enrichment analyses were used to evaluate differentially expressed genes (DEGs). Protein-protein interaction (PPI) networks were built via the STRING database. It was found that tumor necrosis factor (TNF) signaling pathway, cytokine-cytokine receptor interaction, and nuclear factor-kappa B (NF-kappaB) signaling pathway were associated with the therapeutic effects of oridonin in OSCC. Three key genes (BIRC3, TNFSF10, and BCL6) were found to associate with cell apoptosis in OSCC cells treated with oridonin. Quantitative PCR assays verified the expression of apoptosis-related DEGs: TNFSF10, BIRC3, AIFM2, BCL6, BCL2L2, and Bax. Western blots were employed for verifying proteins expression associated with DEGs: cleaved caspase 3, Bax, Bcl-w, anti-cIAP2, and anti-TRAIL. In conclusion, our findings reveal the molecular pathways and targets by which oridonin can treat and induce cytotoxic effects in OSCC: by affecting the signaling including TNF, NF-κB, and cytokine-cytokine receptor interaction and by regulating the key gene BIRC3, TNFSF10, and BCL6. It should be noted that further clinical trial validation is very necessary. Combined with current research trends, our existing research may provide innovative research drugs for the treatment of OSCC.

AKT1 regulates UHRF1 protein stability and promotes the resistance to abiraterone in prostate cancer.

Oncogenic activation of PI3K/AKT signaling pathway, together with epigenetic aberrations are the characters of castration-resistant prostate cancer (CRPC). UHRF1 as a key epigenetic regulator, plays a critical role in prostate cancer (PCa) development, and its expression is positively correlated with the degree of malignancy. In this present study we investigated the potential regulatory mechanism of AKT1 on UHRF1, and further validated the in vitro and in vivo anticancer efficacy of AKT phosphorylation inhibitor MK2206 in combination with abiraterone. Both UHRF1 and p-AKT aberrantly overexpressed in the abiraterone-resistant PCa cells. Further studies revealed that AKT1 protein interacts with UHRF1, and AKT1 directly phosphorylates UHRF1 via the site Thr-210. MK2206 induced UHRF1 protein degradation by inhibiting AKT1-induced UHRF1 phosphorylation, and then reduced the interaction between UHRF1 and deubiquitinase USP7, while promoted the interaction between UHRF1 and E3 ubiquitin protein ligase BTRC. MK2206 significantly promoted the sensitivity of abiraterone-refractory PCa cells and xenografts to abiraterone by decreasing UHRF1 protein level, and reversed the phenotype of NEPC, evently induced cellular senescence and cell apoptosis. Altogether, our present study for the first time revealed a novel molecular mechanism of abiraterone resistance through PI3K/AKT-UHRF1 pathway, and provided a novel therapeutic modality by targeting PI3K/AKT1 to promote the drug sensitivity of abiraterone in PCa patients.

Diosgenin inhibits prostate cancer progression by inducing UHRF1 protein degradation.

Prostate cancer (PCa) represents the second cause of cancer death in adult men. Aberrant overexpression of UHRF1 has been reported in several cancer types, and is regarded as a novel drug target for cancer therapy. Nevertheless, no UHRF1-targeted small molecule inhibitor has been testing in clinical trials. Traditional Chinese medicine (TCM) prescriptions have a long history for the treatment of PCa in China, and Chinese herbal extracts are important resources for new drug discovery. In the present study, we first screened the potentially effective components from the commonly used TCMs for PCa treatment in clinic by using network pharmacology together with molecular docking. We identified diosgenin (DSG) as a small molecule natural compound specifically targeting UHRF1 protein. Furthermore, we validated the results by using the wet lab experiments. DSG, by directly binding UHRF1 protein, induced UHRF1 protein degradation through the ubiquitin-proteasome pathway. Importantly, DSG induced UHRF1 protein degradation by reducing the protein interaction with a deubiquitinase USP7. DSG reduced the level of genomic DNA methylation, and elevated the expression of such tumor suppressor genes as p21, p16 and LXN, thereby resulting in cell cycle arrest, cellular senescence and the inhibition of xenograft tumor growth. We here presented the first report that DSG specifically induced UHRF1 protein degradation, thereby revealing a novel anticancer mechanism of DSG. Altogether, this present study provided a promising strategy to discover new molecule-targeted drugs from small-molecule natural products.

Norcantharidin promotes cancer radiosensitization through Cullin1 neddylation-mediated CDC6 protein degradation.

Radiotherapy (RT) is a conventional cancer therapeutic modality. However, cancer cells tend to develop radioresistance after a period of treatment. Diagnostic markers and therapeutic targets for radiosensitivity are severely lacking. Our recently published studies demonstrated that the cell division cycle (CDC6) is a critical molecule contributing to radioresistance, and maybe a potential therapeutic target to overcome radioresistance. In the present study, we for the first time reported that Norcantharidin (NCTD), a demethylated form of cantharidin, re-sensitized radioresistant cancer cells to overcome radioresistance, and synergistically promoted irradiation (IR)-induced cell killing and apoptosis by inducing CDC6 protein degradation. Mechanistically, NCTD induced CDC6 protein degradation through the ubiquitin-proteasome pathways. By using small interfering RNA (siRNA) interference or small compound inhibitors, we further determined that NCTD induced CDC6 protein degradation through a neddylation-dependent pathway, but not through Huwe1, Cyclin F, and APC/C-mediated ubiquitin-proteasome pathways. We screened the six most relevant Cullin subunits (CUL1, 2, 3, 4A, 4B, and 5) using siRNAs. The knockdown of Cullin1 but not the other five cullins remarkably elevated CDC6 protein levels. NCTD promoted the binding of Cullin1 to CDC6, thereby promoting CDC6 protein degradation through a Cullin1 neddylation-mediated ubiquitin-proteasome pathway. NCTD can be used in combination with radiotherapy to achieve better anticancer efficacy, or work as a radiosensitizer to overcome cancer radioresistance.

ERK-mediated Cytoplasmic Retention of USP11 Contributes to Breast Cancer Cell Proliferation by Stabilizing Cytoplasmic p21.

Breast cancer ranks as the most frequently diagnosed cancer among women worldwide. Elevated cytoplasmic p21 levels are often found in breast cancer tissues and related to a poor prognosis. However, the underlying mechanisms that lead to the stabilization of cytoplasmic p21 protein, which normally has a very short half-life, remain obscure. In this study, we found that there was a strong correlation between p21 and USP11 in the cytoplasm of breast cancer tissues and cells. Furthermore, we revealed that ERK1/2 phosphorylated USP11 at the Ser905 site, which promoted the cytoplasmic localization of USP11. In the cytoplasm, USP11 colocalized and interacted with p21. As a result, USP11 catalyzed the removal of polyubiquitin chains bound to cytoplasmic p21 and resulted in its stabilization. Functionally, USP11-mediated stabilization of cytoplasmic p21 induced breast cancer cell proliferation in vitro and in vivo. Our findings provide the first evidence that ubiquitinated p21 in the cytoplasm can be recycled through USP11-mediated deubiquitination, and we identified the USP11-p21 axis in the cytoplasm as a potential therapeutic target for breast cancer control.

Norcantharidin counteracts acquired everolimus resistance in renal cell carcinoma by dual inhibition of mammalian target of rapamycin complex 1 and complex 2 pathways in Vitro.

Everolimus, an oral mammalian target of rapamycin complex 1 (mTORC1) inhibitor, presents a therapeutic option in metastatic renal cell carcinoma (RCC) patients who were intolerant to, or previously failed, immune- and vascular endothelial growth factor-targeted therapies. However, the onset of drug resistance limits its clinical use. One possible mechanism underpinning the resistance is that inhibiting mTORC1 by everolimus results in mTORC2-dependent activation of v-Akt murine thymoma viral oncogene (AKT) and upregulation of hypoxia-inducible transcription factors (HIF). Norcantharidin (NCTD) is a demethylated derivative of cantharidin with antitumor properties which is an active ingredient of the traditional Chinese medicine Mylabris. In this study, everolimus-resistant RCC cells (786-O-R) obtained by chronic everolimus treatment revealed higher level of HIF2α and over-activated mTORC2 pathway and NCTD inhibits cell proliferation in both everolimus-resistant and -sensitive RCC cells by arresting cell cycle in G0/G1 phase and reducing cell cycle-related proteins of C-Myc and cyclin D. Furthermore, NCTD shows synergistic anticancer effects combined with everolimus in everolimus-resistant 786-O-R cells. Mechanically, NCTD repressed both mTORC1 and mTORC2 signaling pathways as well as downstream molecular signaling pathways, such as p-4EBP1, p-AKT, HIF1α and HIF2α. Our findings provide sound evidence that combination of NCTD and everolimus is a potential therapeutic strategy for treating RCC and overcoming everolimus resistance by dual inhibition of mTORC1 and mTORC2.

Roles of Key Epigenetic Regulators in the Gene Transcription and Progression of Prostate Cancer.

Prostate cancer (PCa) is a top-incidence malignancy, and the second most common cause of death amongst American men and the fifth leading cause of cancer death in men around the world. Androgen receptor (AR), the key transcription factor, is critical for the progression of PCa by regulating a series of target genes by androgen stimulation. A number of co-regulators of AR, including co-activators or co-repressors, have been implicated in AR-mediated gene transcription and PCa progression. Epigenetic regulators, by modifying chromatin integrity and accessibility for transcription regulation without altering DNA sequences, influence the transcriptional activity of AR and further regulate the gene expression of AR target genes in determining cell fate, PCa progression and therapeutic response. In this review, we summarized the structural interaction of AR and epigenetic regulators including histone or DNA methylation, histone acetylation or non-coding RNA, and functional synergy in PCa progression. Importantly, epigenetic regulators have been validated as diagnostic markers and therapeutic targets. A series of epigenetic target drugs have been developed, and have demonstrated the potential to treat PCa alone or in combination with antiandrogens.

Aptamer Enables Consistent Maytansine Delivery through Maintaining Receptor Homeostasis for HER2 Targeted Cancer Therapy.

Although the extensive clinical use of the ADC trastuzumab-DM1(T-DM1) for human epidermal growth factor receptor 2 (HER2) targeted cancer therapy, many patients who initially respond to T-DM1 treatment eventually met the insufficient efficacy issue, which is partly attributed to the decreased amount of surface HER2 caused by HER2 degradation in target cells. In our study, we have engineered a HER2 targeted DNA aptamer-DM1 conjugate (HApDC) that can maintain the homeostasis of surface HER2 on the target cancer cell. These conclusions are supported by determining the efficient internalization of HApDC into HER2 overexpressed BT474 and SKBR3 cancer cell lines and by identifying the membranal HER2 level on HApDC-treated BT474 cells. Consistent with the impressive in vitro properties of our newly developed anticancer agent, DM1 could precisely be delivered to the tumor tissue in BT474 xenografted mouse models, because of the specific recognition of aptamer. Noteworthy, HApDC exhibited excellent in vivo tumor inhibition function with much lower healthy organ toxicity, compared with the free drug, which might be explained by the persistently targeted DM1 delivery, which is attributed to the remaining HER2 levels on cells.

NONO and tumorigenesis: More than splicing.

The non-POU domain-containing octamer-binding protein NONO/p54nrb , which belongs to the Drosophila behaviour/human splicing (DBHS) family, is a multifunctional nuclear protein rarely functioning alone. Emerging solid evidences showed that NONO engages in almost every step of gene regulation, including but not limited to mRNA splicing, DNA unwinding, transcriptional regulation, nuclear retention of defective RNA and DNA repair. NONO is involved in many biological processes including cell proliferation, apoptosis, migration and DNA damage repair. Dysregulation of NONO has been found in many types of cancer. In this review, we summarize the current and fast-growing knowledge about the regulation of NONO, its biological function and implications in tumorigenesis and cancer progression. Overall, significant findings about the roles of NONO have been made, which might make NONO to be a new biomarker or/and a possible therapeutic target for cancers.

Deubiquitinase DUB3 Regulates Cell Cycle Progression via Stabilizing Cyclin A for Proliferation of Non-Small Cell Lung Cancer Cells.

The deubiquitinase DUB3 is frequently overexpressed in non-small cell lung cancer (NSCLC) and contributes to its malignant phenotype. However, the underlying molecular mechanism of DUB3 in NSCLC is largely unknown. In this study, we report that DUB3 regulates cell cycle progression by deubiquitinating cyclin A that links to proliferation of NSCLC cells. We found that knockdown of DUB3 decreases cyclin A levels, whereas overexpression of DUB3 strongly increases cyclin A levels. Mechanistically, DUB3 interacts with cyclin A, which removes the polyubiquitin chains conjugated onto cyclin A and stabilizes the cyclin A protein. Furthermore, we demonstrate that DUB3 regulates cell cycle progression by stabilizing cyclin A, because ablation of DUB3 arrests cell cycle from G0/G1 to S phase and the resulting effect can be rescued by introducing cyclin A into NSCLC cells. Functionally, we found that the effect of DUB3 on cyclin A mediates proliferation of NSCLC cells. Moreover, a significant correlation between DUB3 abundance and cyclin A expression levels were also found in NSCLC samples. Taken together, these results reveal that DUB3 functions as a novel cyclin A regulator through maintaining cyclin A stability, and that the DUB3-cyclin A signaling axis plays a critical role in cell cycle progression for proliferation of NSCLC.

Characterization of a DNA Aptamer for Ovarian Cancer Clinical Tissue Recognition and in Vivo Imaging.

BACKGROUNDS/AIMS: Ovarian cancer is the most lethal gynaecologic malignancy and is difficult to detect early. The inefficient early diagnosis of ovarian cancer is the main contributor to its high mortality rate. Aptamers, as chemical antibodies, are single-stranded DNA or RNA oligonucleotides that target cells or molecules with high affinity. METHODS: Binding ability of R13 was measured by flow cytometry analysis. Stability of R13 was tested in blood serum of an ovarian cancer patient. Internalization of R13 was verified by confocal microscope imaging. 80 cases ovarian cancer tissues, 10 cases normal ovary tissues in a microarray and 6 fallopian tube tissues were prepared for this study. R13's target ability was further confirmed in vivo tumor models in NOD/SCID mice. RESULTS: In this study, we found aptamer R13 bound to ovarian cancer cells with dissociation constants in the nanomolar range. Moreover, these results were further confirmed by tissue imaging. Next we demonstrated that the targets of R13 are membrane proteins and that its internalization occurs in a caveolae-mediated and clathrin-mediated manner. The target function of R13 was determined by imaging A2780 tumours in mouse models. CONCLUSION: These findings suggest that R13 is a promising novel tool to diagnose and deliver drugs to treat ovarian cancer.

In Situ Imaging of Furin Activity with a Highly Stable Probe by Releasing of Precipitating Fluorochrome.

Furin, a kind of trans-Golgi proprotein convertases, plays important role in various physiological processes. It is overexpressed in many cancers and relates to tumor growth and migration. In situ detection and imaging of furin is of great significance for obtaining real-time information about its activity. However, the previously reported fluorescent probes for furin usually failed to realize in situ detection and long-term bioimaging, because these probes are based on water-soluble fluorophores, which tend to diffuse away from the reaction sites after converted by furin. Such a problem can be addressed by designing a probe, which releases a precipitating fluorophore upon furin conversion. Herein, we developed a probe HPQF for in situ detection of endogenous furin activity and long-term bioimaging by integrating a strictly insoluble solid-state fluorophore 6-chloro-2-(2-hydroxyphenyl) quinazolin-4(3H)-one (Cl-HPQ) with a furin specific peptide substrate (RVRR) through a self-immolative linker. The HPQF probe shows high selectivity and sensitivity to furin. Upon converted by furin, HPQF releases free Cl-HPQ, which precipitates near the enzyme active site. The precipitates emit bright solid-state fluorescence for in situ imaging. HPQF could truly visualize the location of intracellular furin, which was further confirmed by colocalization and immunofluorescence experiments. Excitingly, the long-term bioimaging was also achieved benefiting from its outstanding signal-stability and antidiffusion ability. HPQF was further utilized to monitor the level change of furin under stabilizing of hypoxia-inducible factor (HIF) regulated by cobalt chloride (CoCl2) as well as visualization of furin in MDA-MB-468 cell tumor tissues.

Molecular Recognition and In-Vitro-Targeted Inhibition of Renal Cell Carcinoma Using a DNA Aptamer.

Renal cell carcinoma (RCC) is the most common malignant tumor of the urinary system, and it has a high frequency of local invasion and distant metastasis. Although multiple advances have been made in the diagnosis and therapy of RCC, the vast majority of patients with metastatic RCC remain incurable. In this study, an aptamer named SW-4 against RCC 786-O cells was identified from a known sequence pool. The identified aptamer exhibited high binding affinity for target cells with dissociation constants in the nanomolar range. Binding analysis revealed that SW-4 only bound to RCC 786-O cells, but not HEK293T cells or human proximal tubular HK-2 cells, indicating that SW-4 has excellent binding selectivity. By sequence optimization, the 26-nt truncated SW-4b demonstrated improved binding affinity, and it was internalized into target cells via caveolae-mediated endocytosis in a temperature-dependent manner. Furthermore, fluorescence imaging confirmed that SW-4b accumulated at tumor sites in 786-O xenograft nude mice models and specifically recognized clinical RCC tissues. Meanwhile, SW-4b inhibited proliferation of 786-O cells by arresting cell cycle progression at the S phase. Taken together, these results indicate that SW-4b is a potential candidate for development into a novel tool for diagnosis and targeted therapy of RCC.

Deubiquitylation and stabilization of p21 by USP11 is critical for cell-cycle progression and DNA damage responses.

p21WAF1/CIP1 is a broad-acting cyclin-dependent kinase inhibitor. Its stability is essential for proper cell-cycle progression and cell fate decision. Ubiquitylation by the multiple E3 ubiquitin ligase complexes is the major regulatory mechanism of p21, which induces p21 degradation. However, it is unclear whether ubiquitylated p21 can be recycled. In this study, we report USP11 as a deubiquitylase of p21. In the nucleus, USP11 binds to p21, catalyzes the removal of polyubiquitin chains conjugated onto p21, and stabilizes p21 protein. As a result, USP11 reverses p21 polyubiquitylation and degradation mediated by SCFSKP2, CRL4CDT2, and APC/CCDC20 in a cell-cycle-independent manner. Loss of USP11 causes the destabilization of p21 and induces the G1/S transition in unperturbed cells. Furthermore, p21 accumulation mediated by DNA damage is completely abolished in cells depleted of USP11, which results in abrogation of the G2 checkpoint and induction of apoptosis. Functionally, USP11-mediated stabilization of p21 inhibits cell proliferation and tumorigenesis in vivo. These findings reveal an important mechanism by which p21 can be stabilized by direct deubiquitylation, and they pinpoint a crucial role of the USP11-p21 axis in regulating cell-cycle progression and DNA damage responses.

WDR79 mediates the proliferation of non-small cell lung cancer cells by regulating the stability of UHRF1.

WD repeat protein 79 (WDR79) is a member of the WD-repeat protein family characterized by the presence of a series of WD-repeat domains and is a scaffold protein that participates in telomerase assembly, Cajal body formation and DNA double strand break repair. Although previous studies have revealed that WDR79 is frequently overexpressed in non-small cell lung cancer (NSCLC) and promotes the proliferation of NSCLC cells, the underlying mechanism responsible for WDR79-mediated NSCLC proliferation is not fully understood. In this study, we report a novel molecular function of WDR79 that mediates NSCLC cell proliferation by controlling the stability of UHRF1. In the nucleus, WDR79 colocalized and interacted with UHRF1. As a result, overexpression of WDR79 stabilized UHRF1, whereas ablation of WDR79 decreased the level of UHRF1. Meanwhile, we showed that WDR79 can protect UHRF1 from poly-ubiquitination-mediated proteolysis, which facilitated the stabilization of UHRF1. We further demonstrated that WDR79 exerts a proliferation effect on NSCLC cells by stabilizing UHRF1. These findings reveal that WDR79 is a novel UHRF1 regulator by maintaining UHRF1 stability, and they also provide a clue as to how to explore WDR79 for potential therapeutic application in NSCLC.

Efficient Two-Photon Fluorescent Probe for Glutathione S-Transferase Detection and Imaging in Drug-Induced Liver Injury Sample.

Drug-induced liver injury (DILI) is a potential complication of any prescribed medication. So far, the diagnosis of DILI is still a clinical challenge due to the lack of efficient diagnosis method. Glutathione S-transferase (GST), with a high concentration in liver cytosol, can reduce toxicity and facilitate urinary excretion by catalyzing the conjugation of glutathione (GSH) with reactive metabolites in liver. When liver is seriously damaged, GST and GSH will be released into plasma from liver cytosol, which caused a lower GST activity in liver cytosol. Therefore, monitoring the level of GST activity in liver tissue may be a potential strategy for diagnosis of DILI. Here, we reported a two-photon probe P-GST for GST activity detection for the first time. In the proposed design, a donor-π-acceptor (D-π-A) structured naphthalimide derivative with efficient two-photon properties was chosen as the fluorescent group, and a 2,4-dinitrobenzenesulfonate group was employed as the GST recognition unit, which also acted as the fluorescence quencher. In the present of GST and GSH, the recognition unit was removed and the fluorophore was released, causing a 40-fold enhancement of fluorescence signal with a detection limit of 35 ng/mL. At last, P-GST was successfully applied in two-photon imaging of GST in cells and DILI samples, which demonstrated its practical application in complex biosystems as a potential method for diagnosis of DILI.

WDR79 promotes the proliferation of non-small cell lung cancer cells via USP7-mediated regulation of the Mdm2-p53 pathway.

WD repeat protein 79 (WDR79) is a member of the WD-repeat protein family and functions as a scaffold protein during telomerase assembly, Cajal body formation and DNA double strand break repair. We have previously shown that WDR79 is frequently overexpressed in cell lines and tissues derived from non-small cell lung cancer (NSCLC) and it accelerates cell proliferation in NSCLC. However, the detailed mechanism underlying the role of WDR79 in the proliferation of NSCLC cells remains unclear. Here, we report the discovery of a molecular interaction between WDR79 and USP7 and show its functional significance in linking the Mdm2-p53 pathway to the proliferation of NSCLC cells. We found that WDR79 colocalized and interacted with USP7 in the nucleus of NSCLC cells. This event, in turn, reduced the ubiquitination of Mdm2 and p53, thereby increasing the stability and extending the half-life of the two proteins. We further found that the functional effects of WDR79 depended upon USP7, because the knockdown of USP7 resulted in their attenuation. Finally, we demonstrated that WDR79 promoted the proliferation of NSCLC cells via USP7. Taken together, our findings reveal a novel molecular function of WDR79 and may lead to broadly applicable and innovative therapeutic avenues for NSCLC.